The Collaborative International Dictionary of English v.0.48:

Sanctimonious \Sanc`ti*mo"ni*ous\, a. [See Sanctimony.]
   1. Possessing sanctimony; holy; sacred; saintly. --Shak.
      [1913 Webster]

   2. Making a show of sanctity; affecting saintliness;
      hypocritically devout or pious. "Like the sanctimonious
      pirate." --Shak.
      [1913 Webster] -- Sanc`ti*mo"ni*ous*ly, adv. --
      Sanc`ti*mo"ni*ous*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

sanctimonious
    adj 1: excessively or hypocritically pious; "a sickening
           sanctimonious smile" [syn: holier-than-thou,
           pietistic, pietistical, pharisaic, pharisaical,
           sanctimonious, self-righteous]